In U.S. Pat. No. 4,507,913 (which is incorporated by reference herein) and in parent application Ser. No. 677,487 filed Dec. 3, 1984, methods and apparatus are provided for efficiently and effectively producing yarn having properties approaching those of ring spun yarn, but at much greater speeds. The basic technique disclosed in said patent and parent application is known as "vacuum spinning", and has a number of advantages compared to conventional techniques.
Until relatively recently, ring spinning equipment has made up approximately 90 percent of all spinning equipment. However several new high speed procedures have recently been utilized including open end spinning, friction spinning, hollow core spinning, and air jet spinning. None of these new commercial systems has been successful in the production of long staple yarn, however, especially for apparel fabrics. However vacuum spinning is capable of producing long stable yarn suitable for use in apparel fabrics, the yarn approaching the properties of ring spun yarn.
Vacuum spinning has a number of advantages compared to conventional ring spinning. These include the following: Productivity can be expected to be at least 6-8 times that of commercial ring spinning. Despite this increased productivity, the properties of the yarn are more like ring spun yarn than open end or air jet type yarns. The horsepower per pound of yarn produced is considerably less than that for air jet spinning using compressed air. Vacuum spinning lends itself to automatic end piece-up, automatic slubbing, automatic adaptation, the production of large delivery packages, and the utilization of large supply packages (e.g. 25 lb. cans of sliver). A wide count range can be provided on long staple yarns, at least 1/8's to 1/60's on 55 percent polyester/45 percent wool, and at least 1/8's to 1/40's on 100 percent wool. There are lower labor costs per pound of yarn produced compared to ring spun yarn.
Further advantages of the invention are as follows: The process lends itself to high draft ratios (e.g. 10-80), can be modified to run both long and short staple yarns, and can make yarn having either "S" or "Z" twist. A number of unique novelty yarns can be produced, such as described in co-pending application Ser. No. 680,510 filed Dec. 11, 1984. The apparatus is simple and easy to maintain, and the noise level can be controlled by locating the vacuum pump in a separate location, to thereby ensure compliance with OSHA regulations. The apparatus runs cleanly since the vacuum automatically removes lint fly, and like contaminants, and oily waste is not introduced. Waste is reduced due to draft zone stoppage on end breaks, with a reduction in end breakage of about 400 percent compared to ring spinning since there is no tension in the yarn. Also thread-up of the broken ends can be accomplished with minimum operator intervention. The system can be run using higher weight sliver (e.g. 55 grains per yarn compared to 35-40 grains per yarn which is conventional), and carpet yarn can be produced too by lengthening the draft zone and providing a larger nozzle. Yarn steaming may not be required for most counts-blends for handling, although it may be required for uniform dyeability, and steaming is easy to effect.
The apparatus and method according to the present application have basically all the same advantages described above with respect to vacuum spinning in general. Additionally, according to the present invention in the production of yarn from roving it is possible to construct the "nozzle" of the vacuum spinning apparatus in a simpler and more advantageous manner. By providing an interior generally conically shaped vacuum reservoir, instead of a spherical vacuum reservoir, ease of production is facilitated and a yarn having a slightly better break strength can be produced.
Also according to the present invention the production of yarn directly from sliver is faciliated. According to the present invention a method of spinning yarn is provided which includes the steps of: drafting a sliver of fibers so as to produce a drafted sliver; feeding the drafted sliver in a linear direction in a fiber mass; passing the fiber mass into the interior of a hollow shaft ("nozzle") rotatable about an axis coincident with the direction of movement of the fibers; applying a vacuum to the circumferential exterior of a perforated portion of the shaft so that some of the fiber mass inside the shaft is attracted toward the shaft interior surface; and rotating the shaft at high speed (e.g. 3550 rpm) so that the ends of certain of the fibers interior of the shaft rotate with the shaft as they move linearly, and so that those ends extend into an interior chamber of the hollow shaft so as to ultimately wrap around other portions of the fiber mass, to produce a final yarn. Utilizing the method of the invention it is possible to produce a final yarn having a break strength comparable to a break strength of at least 500 grams per denier for a yarn produced from 1/19's count fibers of 55 percent polyester and 45 percent wool.
The particular "nozzle" for producing yarn having good strength properties directly from sliver, according to the present invention, preferably includes a generally conically shaped interior chamber. The perforations in communication with the interior chamber are generally wedge-shaped, and the size of the interior passageway in the shaft adjacent the first end thereof is very large compared to the diameter of the shaft passageway between the interior chamber and the second end of the shaft, and may have the shape of a right circular cone frustum. The interior chamber is dimensioned so that it is large enough to allow free fiber movement so that the fibers will be lifted up and wrap around a core of the fiber mass more securely, however the interior chamber should not be so big that the fibers will be pulled through the perforations by the vacuum source. The perforations and the passageway between the first end of the shaft and the perforations, are dimensioned so that optimal wrapping action can be achieved. That is, the dimensions are large enough so that they allow sufficient air flow that they do not prevent the attainment of optimal fiber wrapping action. In this way optimal wrap for any given application may be achieved.
It is the primary object of the present invention to provide effective refinements and modifications of methods and apparatus for vacuum spinning of yarn. This and other objects of the invention will become clear from an inspection of the detailed description, and from the appended claims.